The original title for this story was "Transitioning from IPv4 to IPv6," but when we started researching, we quickly realized that most organizations are adopting an outside-in strategy, rather than moving over from all-IPv4 to all-IPv6 deployments. This means that they're often taking steps to accommodate incoming and outgoing IPv6 traffic at the organizational boundary and translating between the two stacks, or tunneling one protocol over another, for internal access and use. The majority of internal clients and other nodes are using IPv4, with increasing use of IPv6 in dual-stack environments (environments that run IPv4 and IPv6 protocol stacks side-by-side).

IPv6 transitioning tools and technologies

To bring IPv6 into a mix that also includes IPv4, certain so-called "transition tools" prove necessary. The Internet Request for Comment (RFC) 1933 defines these capabilities as essential to any IPv6 transition:

When upgrading hosts and routers to IPv6, they will retain IPv4 capability as well. This permits IPv6 to provide compatibility for IPv4 protocols and applications alike. Such hosts and routers are called dual-stack, because they run IPv6 alongside IPv4 in parallel.